Pond plants

Plants give visual interest to a pond, encourage wildlife and can help keep water clear. Choosing the right plants greatly adds to your enjoyment of the pond as well as that of visiting or resident wildlife.

Introduction

With the extensive range of pond plants available in nurseries and garden centres, selecting the right plants can be daunting. The vigour of the plants and avoidance of unwanted invasive types as well as the suitability in varying depths needs to be taken into consideration.

Practical considerations

When choosing plantings for ponds or water features, there are number of things to bear in mind;

  • Decide whether you would like your plants to be native water plants or exotics. Freshwater Habitats Trust (was Pond Conservation) has produced a leaflet ‘Planting-up Ponds’ with suggestions for native species that will attract wildlife
  • Consider not planting up a pond and allowing plants to colonise naturally. Most gardeners, however, are keen to get going with planting up from the start
  • Choose the right plants for the depth of water. There are waterlilies, for example suitable for all depths, from 10cm deep to 1.2m and deeper
  • Some water plants and marginals are vigorous, spreading via roots or by self-seeding such as in the case of sweet flag (Acorus calamus ‘Argenteostriatus’). This can be useful in larger water gardens, but if you have a small pond, consider the potential inhabitants carefully
  • It is good practice to quarantine purchases for a few weeks before introducing them. Many potentially invasive species, such as Crassula helmsii, are introduced into ponds unknowingly as contaminants on newly-acquired water plants
  • In recent years a growing problem has been posed by a number of introduced aquatic plants. These can be very invasive and can have seriously detrimental effects on gardens and the wider landscape. In early 2013 Defra announced a ban on sale of five of the worst invasive water plants in the UK

Suitable plants

Choose plants that give contrasts in foliage as well as variation in flowering times to give as long a display as possible. The following list gives a selection of plants that garden centres, nurseries and pond plant specialists are likely to stock.

Submerged plants (aka oxygenators)

Submerged plants produce oxygen during the day and provide cover for aquatic life

Callitriche hermaphroditica (syn. C. autumnalis) (water starwort): Also suitable for running water (may become too invasive for small pools)
Ceratophyllum demersum, C. submersum (hornwort): Suitable for deep water, free floating
Fontinalis antipyretica (willow moss): Best planted attached to a stone, suitable for running water
Groenlandia densa (syn. Potamogeton densus) (frog’s lettuce)
Hippuris vulgaris (mare’s-tail)
Hottonia palustris (water violet): Do not move or plant in summer; lilac flowers in summer
Myriophyllum spicatum, M. verticillatum (water milfoils)
Lobelia dortmanna (water lobelia): Pale violet-blue flowers (may become too invasive for small pools
Potamogeton crispus, P. pectinatus (may become too invasive for small pools)
Ranunculus aquatilis (water crowfoot): White flowers in May; also suitable for running water

Floating plants

Floating plants do not need anchorage in soil. Their presence on the surface reduces the amount of sunlight penetrating the water and keeps the water cooler, discouraging algae. Aim to keep around 50% of the surface clear of vegetation, if necessary by thinning occasionally during the summer.

Azolla mexicana: Severe winters may kill this plant. Leaves turn reddish in autumn (may become too invasive for small pools)
Hydrocharis morsus-ranae (frogbit): Small white flowers; sinks to the bottom in winter
Stratiotes aloides (water soldier): Floats just below surface; sinks in winter (may become too invasive for small pools)

Marginal Plants

These plants are ornamental in flower and foliage and soften the harsh outlines of pools. They are also valuable for shading pool margins where algae may otherwise multiply in the warm, shallow water. For small pools, plant separately in 15cm (6in) containers and re-pot when overcrowded. Heights given indicate length of leaves or flowers above the water surface.

1. Water 30cm (1ft) or more

Alisma plantago-aquatica (great water plantain): White flowers. Remove dead flowers to prevent seeding. Height 60-90cm (2-3ft) (may become too invasive for small pools)
Aponogeton distachyos (water hawthorn): Tuberous. Fragrant white flowers. Water snails will feed on this plant and kill it. Height 5cm (2in)

2. Water 15-30cm (6in-1ft) deep

Menyanthes trifoliata (bog bean): Olive-green trefoil leaves, pinkish white flowers in spring. Height 15cm (6in
Ranunculus flammula (spearwort): Bright yellow flowers. Height 70cms (2ft 4in)
Thalia dealbata: Bold blue-green leaves. Height 1.5m (5ft)
Zantedeschia aethiopica (arum lily) AGM: White spathe, golden spadix, fragrant. ‘Crowborough’ is the hardiest form. Height 45cm (1½ft)

3. Water 5-15cm (2-6in)

Acorus calamus ‘Argenteostriatus’ (sweet flag): Foliage variegated creamy-white, greenish flowers, can be invasive. Height 60cm (2ft) (may become too invasive for small pools)
Butomus umbellatus AGM (flowering rush): Pink flowers in summer, like a miniature agapanthus. Height 60-75cm (2-2½ft)
Calla palustris (bog arum): Glossy leaves, white flowers in summer, followed by spikes of red berries. Height 22cm (9in)
Glyceria maxima var. variegata: Yellow and white variegated leaves, rosy autumn leaf colour. Height 60cm (2ft) (may become too invasive for small pools)
Iris laevigata AGM: Rich blue flowers in June. Height 60-75cm (2-2½ft)
I. pseudacorus AGM (yellow flag): Yellow flowers. Height 90cm (3ft) (may become too invasive for small pools)
Juncus effusus f. spiralis (corkscrew rush): Stems twisted in a corkscrew manner. Height 45cm (1½ft)
Lobelia cardinalis AGM: Purplish foliage, scarlet flowers. Needs winter frost protection in most regions. Height 60-75cm (2-2½ft)
Lysichiton camtschatcensis AGM: white flowers. Height 30cm (1ft)
Orontium aquaticum (golden club): Shiny leaves, yellow flowers in a spike. Height 10-12.5cm (4-5in)
Pontederia cordata AGM (pickerel weed): Glossy leaves, blue flowers in late summer. Height 45-60cm (1½ft-2ft)
Ranunculus lingua ‘Grandiflorus’ (giant water buttercup): Reddish stems, large yellow buttercup flowers. Height 1.2m-1.5m (4–5ft)
Sagittaria latifolia: White flowers in late summer, autumn foliage colour. Height 30-90cm (1-3ft) (may become too invasive for small pools)
S. sagittifolia ‘Flore Pleno’: Double white flowers. Height 75cm (2½ft)
Schoenoplectus lacustris subsp. tabernaemontani ‘Albescens’: Stems sulphur white when young, darkening to green. Height 1.2m-1.5m (4-5ft) (may become too invasive for small pools)
S. lacustris subsp. tabernaemontani ‘Zebrinus’ (zebra rush): White stems banded with green. Height 45cm-1.2m (1½-4ft)
Typha angustifolia: ‘Cat’s tails’ inflorescence. Height 1.2m (4ft) (may become too invasive for small pools)
T. laxmannii: Narrow leaves, ‘cat’s tails’ inflorescence. Height 90-1.2m (3-4ft)
T. minima: Brown ‘cat’s tails’ inflorescence. Height 30-45cm (1-1½ft)

4. Very shallow water (less than 5cm [2in] and mud)

Acorus gramineus ‘Variegatus’:
Leaves striped pale yellow. Height 20-30cm (8in-1ft)
A. gramineus var. pusillus: Forms dense tufts. Height 7.5-10cm (3-4in)
Caltha palustris AGM (marsh marigold): Large golden flowers in March. Height 22.5-30cm (9in-1ft)
Carex elata ‘Aurea’ AGM (Bowles’ golden sedge): Golden foliage. Height 45cm (1½ft)
Carex pendula: Arching stems, drooping brownish spikelets. Height 90cm-1.2m (3-4ft)
C. pseudocyperus: Bright green foliage, dark green spikelets. Height 60-90cm (2-3ft)
Cotula coronopifolia (golden buttons): Annual, sometimes perennial, seeds freely, aromatic foliage, button shaped yellow flowers. Height 15cm (6in)
Houttuynia cordata: Dark green leaves, red stems, white flowers. Height 60cm (2ft) spreads freely. ‘Chameleon’ leaves variegated red and yellow (may become too invasive for small pools)
Iris ensata AGM (Japanese water iris): Blue, red or white flowers. Height 60-90cm (2-3ft)
Iris sibirica AGM: Blue flowers. Height 45cms (1½ft)
Iris versicolor AGM: Violet-blue flowers. Height 60cms (2ft)
Mimulus cardinalis AGM: Orange-red flowers in summer. Needs winter frost protection in most regions. Height 30-45cm (1-1½ft)
M. lewisii AGM: Red or white flowers. Height 30-60cm (1-2ft)
M. luteus: Yellow flowers. Height 30-45cm (1-1½ft)
M. ringens: Violet-blue flowers. Height 45-60cm (1½-2ft)
Myosotis scorpioides (water forget-me-not): Blue flowers in May. Height 23cm (9in)
Saururus cernuus (lizard’s tail): Fragrant white flowers, dark green leaves. Height 15cm (6in)
Veronica beccabunga (brooklime): White-centred blue flowers. Height 10cm (4in)

Some waterlilies

There are many waterlilies available but it is important to choose ones appropriate to the size and depth of pond.

1. Water 75cm-1.2m (2½-4ft) deep

Nymphaea alba: Prolific white flowers
N. ‘Amabilis’: Tulip-shaped flowers, salmon pink
N. ‘Attraction’: Red flowers darkening with age
N. ‘Escarboucle’ AGM: Free flowering, red
N. ‘Gladstoneana’ AGM: Free flowering, white

2. Water 45-75cm (1½-2½ft) deep

Nymphaea ‘Gonnere’ AGM:
Fragrant, white
N. ‘James Brydon’ AGM: Free flowering, red
N. ‘Marliacea Carnea’: White flushed pink
N. ‘Marliacea Chromatella’ AGM: Yellow flowers
N. ‘Masaniello’: Fragrant, pink
N. ‘Rose Arey’: Pink, star-shaped, fragrant flowers
N. ‘William Falconer’: Cherry red

3. Water 30-45cm (1-1½ft) deep

Nymphaea ‘Aurora’: Cream opening yellow to orange
N. ‘Caroliniana Nivea’: Fragrant, white
N. ‘Charlene Strawn’: Lemon yellow
N. ‘Ellisiana’: Red
N. ‘Fire Crest’: Deep pink
N. ‘Froebelii’: Dark red
N. ‘Indiana’: Apricot-orange
N. ‘Laydekeri Fulgens’: Early free-flowering, red
N. ‘Laydekeri Liliacea’: Fragrant, rosy-lilac
N. ‘Lucidia’: Free-flowering, pink
N. ‘Mme Wilfon Gonnère’: Double pink
N. ‘Pink Sensation’: Pink

4. Water 10-30cm (4in-1ft) deep

Nymphaea odorata var minor: Fragrant, pink
N. tetragona: White
N. ‘Pygmaea Helvola’ AGM: Yellow flowers, marbled leaves
N. ‘Pygmaea Rubra’: Free-flowering, red

Waterlily selection from the RHS Find a Plant

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